Safety collar



Sept. 27, 1955 TON 2,719,025

SAFETY CQLLAR INVENTOR. Albert L. Stone,

BY ATTORNE Y.

' SAFETY COLLAR Albert L. .St0ne,.. Redondo Beach, Calif., assignor, by

mesneassignments, to-EssoI-Research and Engineering Company Elizabeth,N. J.,*a'corp0ration of Delaware Application August 22, 1951, SerialNo.243,090

2 Claims. ((-11. 255-23 The present'invention relatesto .a safety collarof the type adapted to be engaged with aspecially prepared drill .collarin order to support 'thedrillicollar in an oil well derrick.

.An object of the present invention is to provide a safety collarfor.use conjunction with a drill collar to prevent the loss of the drillco'llarfin thehole due to release of the slips supporting the drillcollar from .the rotary table. A further object .of thepresenttinvention'is to provide a safety collar which can'beemployed'for grasping the drill collar for raising and'lowering thedrill collar in the borehole. A further object is to provide asafetycollar which is incapable of sliding longitudinally along the drillcollar and which can be applied to the drill collar without resorting tothe usual friction clamps-used forthis purpose.

Briefly, the safety collar in accordance with my invention comprises aplurality ofjaws hingedly connected togetherand adapted to be closed oropened to engage or to release .a drill collar having recesses in itsouter surface forreceipt of load carrying memberscarried by the jaws.For securing the jaws 'in .the closed position, anordinary latch isemployedwhich is capable of being easily latched and unlatched so thatlittle, if any, time is wasted 'in engaging the jaws with anddisengaging them from-the drill collar. 'Itis further contemplated thatmy safety collar may be equipped with a pair of .lifting ears secured tothe 'jaws so that the collar maybe lifted by La suitable hoistingdevice. For the purposes of my invention, itmakes no difference whetherboth these cars are secured to onejaw or whether one ear is secured to.one jaw while the other is:secured to-another jaw solong as the twocars are located at diametrically spaced points lonthe collar.

The .use .of the safety collar of the present invention eliminates anumber of serious disadvantages inherent in the usual practices ofhandling drill collars. pie, inorder toavoid loss of drill collars intothe .bore- For examhole, it has been the common practice to attach tothe iIn additio'nto the'se disadvantages which are inclamp is atfixed tothe drill collar, to attach an adapter 'tothe-drill 'collar'andtotighten the adapter with power tongs. This adapter remains attached tothe stand of drill pipein which .thendrill collar is arranged '-whilethe stand is set back in the derrick, thus keeping idle for long periodsof time a costly piece of equipment on each such stand. -Itis-necessary, -however,to use this adapter inasmuch as thetaforernentionedtclamp acannot'be used as a release their grip on thedrill collar. "modern drill collar possess an area of smaller diameterPatented Sept. 27, 1955 grasping means for lifting the drillpipe standinwhich the .drill collar is arranged.

Another 'difliculty inherent in the modern drill collar comes aboutbecause of the form in'which'it is made.

The modern drill collar is a uniform'cylinder of hardened (steel withscrew threads at both ends. "Because itis'of uniform diameter throughits outer length,it possesses no shoulder of enlarged diameter which can'be relied upon to strike the upper surface of the tapered slips andcause the slips to reset in case the slips-momentarily Neither does theon its outer surface so thatitcan be easily grasped with ,a hoistingdevice although atone time it was the'practice to provide drill collarswith an annular groove and shoulder so that they could 'be easilygraspedwith an elevator or a fishing tool. This 'o'ldertype cannot, of'course,'be used in areas where excessive stresses on' 'drill collarsare common because suchdrill 'collars-fa'ilatthe pointswhere theyaregrooved'inasmuc'h asstressesare concentrated in this area. Accordingly,the modern and shoulder on the drill collar itself. The safety collar ofmy invention makespossible theme of modern'dr'ill collars, only slightlymodified, without resort to an "adapter or a safety clamp of 'the kindhereinbeforementioned.

A description 'of drill collars'will befound inthebo'mposite Catalogueof Oil Field 'and'Pipe Line Equipment,

18th edition (1951'), published'by World Oil, Houston,

Texas, on pages 393 and 2432. Inthe'CompositeCatalogue,'supra, adiscussion is given of the desirable-char- 'acteristics of'drillcollars.

My invention will be explained in detailherein'after withreference tothe drawing which illustrates several embodiments of the'invention andin which:

Fig. 1 is a cross-sectional view of a conventional drill collar'alteredto include spacedrecesses in itsotitersurface;

Fig. 2 is an'end view of thedrill collarshown in -Fig. 1;

Fig. 3 is a plan view of the safety collar of 'myinventi'on with certainparts cut away to better show details 6f construction, the clamp beingin the closed position;

Fig. 4 is a sectional view taken alongthe line IV I V of Fig. '3;

Fig. 5 is aview similar to that ofFig. 4 but illustrating a differentembodiment of the'present invention;

"Fig; 6 is a view similar'to that of Fig. 4 but illustrating a dilferentembodiment of the presentinvention;

Fig. 7 is a part-sectional view illustrating another embodiment ofthepresent invention;

Fig. 8 'is a sectional view "taken along the "lines VIIL-VIII of Fig. 7;

Fig. 9 illustrates one manner in which the device of the'lpresentinvention may be used in conjunction with slips for supporting a drillcollar of the type shown in Fig. l; and

Fig. 10 illustrates another way in which the deviceof the presentinvention may be employed with slipsan'd in conjunction with a drillcollar'of the 'kind illustrated in Fig. 1.

Referring to the drawing, and particularly to Figs. 1, '2, "and 7, thenumeral 10-desi'gr1ates a-conventional drill collar having an upperthreaded end T1 and equipped with'a plurality of sp'acedre'cesses 13.'In Figs. '1 and 2, recesses 13 are shown as shallow depressionsor holesnot unlike the holes drilledin a shaft for re'ceipt 'of a set screw. InFig. 7 recessesld' are'showndnithe form of longitudinal slots. In anyevent, the shape, size, andl'positionof the recess is important. :Therecess should be shaped and located in such a manner that it does notproduce a notched effect in the stress plane of the drill collar. Thismeans that the recess should be placed in the heavy section of the drillcollar well below the normal point of stress in the threaded area. It ispreferable to locate these recesses some distance from the threaded endsso that the threaded ends may be recut and rethreaded from time to timeas required. Furthermore, the recess should be of sufficient size andsufiicient in number to transmit the load from the drill collar throughthe load carrying elements to the safety collar.

The safety collar of the present invention comprises a first jaw formingthe body of the device and a second jaw 21 comprising the gate. Thefirst and second jaws are pivoted to one another by hinge pin 22 whichpasses through the knuckles 23 forming part of gate 20 and knuckles 24forming part of gate 21. Jaws 20 and 21 pivot about the longitudinalaxis of hinge pin 22.

A latch mechanism for holding jaws 20 and 21 in the closed position isprovided, this latching mechanism comprising a latch 25 pivotallymounted on a latch hinge pin 26 to gate 20 and a latch handle 27, whichhandle abuts upon a cooperating latching projection 28 for holding jaws20 and 21 in the closed position, as shown. Jaws 20 and 21 may beallowed to move in the open position by moving latch handle 27 outwardlyabout pivot pin 26 to disengage handle 27 from cooperating latchingprojection 28.

The inner surface 29 of jaw 20 and the inner surface 30 of jaw 21 areeach semi-cylindrical. Load carrying members 31 project inwardly fromjaws 20 and 21 past cylindrical surfaces 29 and 30, respectively, andinto the central opening 32 formed by said cylindrical surfaces whenjaws 20 and 21 are closed. These load carrying members may consist ofset screws as shown in Fig. 4 which extend transversely through jaws 20and 21 to the outer surface 33 thereof. When so arranged, the distanceset screws 31 project beyond surface 29 may be altered from time to timeas desired by applying a suitable tool to slotted head 34 and rotatingthe screw. These load carrying members may also suitably be a metal ball35, as shown in Fig. 5, or a metal cylinder 36, as shown in Fig. 6,properly imbedded in the jaws. In any event, these load carrying membersare located in jaws 20 and 21 so that they project into recesses 13carried on the outer surface of drill collar 10 when jaws 20 and 21 arein the closed position. It will be also understood that rather than theload carrying members being in the forms illustrated in Figs. 4 to 6,inclusive, the load carrying member may be in the form illustrated inFigs. 7 and 8 and designated by the numeral 37. However, a safety collarequipped with load carrying members of the shape illustrated in Fig. 8can be used only if the drill collar has recesses shaped to receive themas are the recesses illustrated in Fig. 7.

While Figs. 3 to 6, inclusive, and Fig. 8 illustrate a safety collarhaving a plurality of load carrying members, it will be understood thatthe safety collar of my invention may be equipped with as few as onesuch member. This is particularly true where a single drill collar isbeing lifted. Of course, a safety collar having a single load carryingmember can be used in conjunction with a drill collar having only onerecess.

For convenience in opening and closing jaws 20 and 21, handles 38 and39, respectively, may be provided. In order to render the safety collarof my invention useful for lifting the drill collar as well as using itfor causing the slips to set to prevent the drill collar from dropping,I provide lifting ears 4'0 and 41. It will be noted that lifting car 40is affixed to jaw 20 while lifting car 41 is affixed to jaw 21, the twocars being positioned at diametrically opposed points on the collar.These lifting ears may be conventional in design and, accordingly, theirconstruction will not be described in detail. It will be understood,however, that rather than having these two lifting ears on the two jaws,both of these ears may be located on the same jaw.

One way in which the safety collar of my invention may be utilized isillustrated in Figs. 9 and 10. Fig. 9 illustrates a drill collar 10 heldin place in a rotary table 50 by means of slips 51. Mounted on drillcollar 10 immediately above slips 51 is a safety collar A while a safetycollar B provided with lifting ears 40 and 41 attached thereto ismounted adjacent the upper end of the drill collar 10 but below thethreaded section 11 thereof. In this arrangement safety collar B can beused as an elevator by attaching lifting links to cars 40 and 41 whilesafety collar A impinges upon the upper surface 51 of slips 51 causingslips 51 to set.

Instead of providing two safety collars, as indicated in Fig. 9, asingle safety collar may be employed, as indicated in Fig. 10. Fig. 10shows a drill collar 10 grasped by means of slips 51 positioned inrotary table 50. A safety collar B having lifting cars 40 and 41 ismounted on drill collar 10. In this arrangement if slips 51 momentarilyrelease drill collar 10 and the drill collar 10 moves downwardlytherethrough, safety collar B will strike the upper surface 51' of slips51 causing said slips to set, that is, again to grasp firmly drillcollar 10. Ears 40 and 41 permit safety collar B to be employed as anelevator by attaching lifting links thereto. Thus, the safety collar maybe used as an elevator as well as a means for causing slip segments toreset when and if they momentarily release their grip on a drill collarto which the safety collar is connected.

It will be apparent that various modifications of the disclosed devicemay be made without departing from the spirit of the present invention.What I wish to claim and to secure by Letters Patent is:

1. In an apparatus for supporting a string of drill pipe having a drillcollar thereon from a rotary table having conventional slips, bushing,and gearing therein for rotating said string of pipe, said drill collarbeing provided on its exterior surface with at least one preformedrecess, the combination with said apparatus of a safety collar attachedto said string of pipe and designed to contact said slips and bushing inthe event of failure of said slips, said safety collar comprising aplurality of jaws pivotally connected to one another, latching meanscarried by said jaws for securing said jaws together for encircling thedrill collar, and at least one member on said jaws extending inwardlyfrom the inner surface thereof and adapted to fit matingly in a recesson the exterior surface of said drill collar when said jaws encirclesaid drill collar.

2. In an apparatus for supporting a string of drill pipe having a drillcollar thereon from a rotary table having conventional slips, bushing,and gearing therein for rotating said string of pipe, said drill collarbeing provided on its exterior surface with at least one preformedrecess located in an unthreaded portion of the drill collar, said recessbeing elongated longitudinally of the drill collar with a surfacedefining said recess being normal to the outer surface of said drillcollar, the combination with said apparatus of a safety collar attachedto said string of pipe and designed to contact said slips and bushing inthe event of failure of said slips, said safety collar comprising aplurality of jaws pivotally connected to one another, latching meanscarried by said jaws for securing said jaws together for encircling thedrill collar, and at least one member on said jaws extending inwardlyfrom the inner surface thereof and adapted to fit matingly in a recessin the exterior surface of said drill collar when said jaws encirclesaid drill collar.

6 Gran Sept. 8, 1936 Wilson Dec. 29, 1936 Vaughn Sept. 21, 1937 BowlesMay 7, 1940 Johnson Nov. 10, 1942 Price Oct. 9, 1945 Schaub Aug. 15,1950 FOREIGN PATENTS Great Britain Mar. 2, 1904 Great Britain Dec. 16,1926

